Crushed-fuel stoker having means for equalizing the distribution of fuel upwardly in the retort



Feb. 14, 1950 c. QulsT 2,497,628

cRUsHED-FUEL sIoxER HAVING MEANS FOR EQUALIZING THE DISTRIBUTION oF FUELuPwARDLY IN THE REToRT Filed OCT.. 17', 1945 2 Sheets-Sheet l SQINVENTOR.

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c. QUlsT 2,497,628 cRUsHED-EUEL sToxER HAVING MEANS FOR EQUALIZING THEDISTRIBUTION 0E FUEL UPwARDLT IN THE EEToRT Filed oct. 17, -1945 2Sheets-Sheet 2 Feb. 14, 1950 INVENTOR. Corneau@ Patented Feb. 14, 1950UNITED STATES `PATENT OFFICE CRUSHED-FUEL STOKER HAVING MEANS FOREQUALIZING THE DISTRIBUTION F FUEL UPWARDLY IN THE RETORT CorneliusQuist, Grand Rapids, Mich., assigner to Holland Furnace Company,Holland, Mich., a corporation of Delaware Application October 17, 1945,Serial No. 622,838

4 Claims. (Cl. 110-45) This invention relates to a stoker for furnacesand other heating units and more particularly to an underfeed stoker inwhich the crushed coal or other solid fuel of suitable fineness isforced upwardly through the retort with a uniform upward filling of theupper portion of the retort.

In stolcers as heretofore known the crushed coal or similar fuel, whenbeing forced upwardly through the retort, under the action of a screw orother means for forcing the fuel from a hopper through the fuel tube,has had a tendency to climb up one side of the retort neck due to therotation of the coal screw. This action causes the coal to move alongone side of the retort more than the other with the result that the coalrises unevenly in the retort. In the present invention I have providedmeans for overcoming this difliculty and causing a uniform and evenupward continuous lling of the upper portion of the ren tort. My presentinvention equalizes the distri bution of the coal so that in the upperportion of the retort all of the coal is moved vertically upward inparallel layers. Segregation of the larger particles of coal isprevented and the coal is kept thoroughly mixed.

Among the objects of my invention are to provide a novel and improvedstoker; to provide a stoker in which coal segregation is eliminated, andin which the coal rises evenly in the retort; to provide a novel form ofretort cooperating with the feed screw of the Stoker to attain such aresult; more particularly to provide a novel form and arrangement ofretort and rib for equalizing the distribution of the coal upwardly inthe retort; to provide means for overcoming the disadvantages andaccomplishing the advantages hereinbefore referred to.

Other objects and advantages will appear from the following detaileddescription, taken in connection with the accompanying drawings,wherein:

Fig. l is a side elevation of a stoker embodying my invention.

Fig. 2 is a longitudinal vertical central section through the retort andadjacent section of the coal tube and associated parts.

Fig. 3 is a top plan view of the retort and adjacent section of the coaltube shown in Fig. 2.

Fig. 4 is a fragmentary longitudinal enlarged section on the line 4 4 ofFig. 2.

Fig. 5 is a section on the line 5--5 of Fig. 2.

While my invention resides in the combination, construction andarrangement of parts illustrated in the accompanying drawings, I haveshown therein for illustrative purposes only, a preferred 2 embodiment,Iand wish it understood that the same is susceptible of modification andchange without departing from the spirit and scope of the appendedclaims.

While I refer herein to crushed coal as the preferred fuel, I wish thisterm to include any other crushed or sufliciently fine and solid fuelthat may be adapted for use in the Stoker shown and described herein.

My improved stoker comprises generally a hop per I, a blower 2, a coaltube 3 and a retort having a bowl 4. Rotatably mounted and extendinglongitudinally in the coal tube 3 is a screw conveyer 5 for conveyingthe crushed coal longitudinally along this tube from the hopper to theretort. A conduit 6 leads from the blower to a sheet metal casing 1 andfrom said c-asing air passes to the upper portion of the retort. Theconduit 6 is preferably placed to one side of the coal tube as indicatedin Fig. 3. The sheet metal casing I is positioned around the coal tube 3and has its side walls spaced a sufficient distance from the sides ofthe coal tube to provide an air passageway on each side of the tube forconducting the air along the coal tube and introducing it into theretort on both sides of the coal tube. Extending longitudinally alongthe top of the coal tube within the casing 1, is a rib 8 whose upperedge is spaced a distance below the top of the casing to permit passageof air from passageway 8' to passageway 8 as well as longitudinally ofthe -coal tube, which air may also pass laterally through any space thatmay be provided between the bottom of the coal tube and the bottom. ofthe casing 1 if desired. These air spaces 8 and 8" (Fig. 3) jointlyconduct the air into space 9 in the hollow sectional casing I0,hereinafter rcferred to as tuyres, positioned around the retort 4 (seeFig. 2) and extending a desired distance thereabove to provide the upperportion II of the retort. Suitably formed in this upper portion of theretort are openings I2 for conducting air under pressure into thefirebed in the top part of the retort. Should it be desired that thefirebed extend somewhat around the outside of the retort top additionalopenings I3 may be provided in the outer tuyre w-alls I0 for directingair under pressure into that portion of the rebed. v

A suitable door III is provided in the top of the hopper I and providedwith suitable hinges (not shown) and a securing latch I5 to hold the lidor cover closed in an air tight condition if desired. A suitable motorI5 is provided adjacent the hopper for rotating the fan blades of theblower 3 2. Gearing 35 between the motor shaft and the feed screwprovides a drive for the screw. As stated, the air conduit from theblower is outside of the coal tube. A suitable door l1 is provided forenabling access to the chamber within which the blower and motor aremounted.

In screw conveyor stokers known prior to my invention there has been anundesirable tendency of the feed screw to feed the coal excessively atAone side of the retort thus giving an uneven distribution of the coalupwardly inthe retort. Thisy greatly lessens the efficiency of the rebedand prevents the desired results of the stoker. In these old stokersheretoforeknown, the coal while being forced forwardly by the screwconveyor, has a tendency to climb up one side of the retort neck due tothe rotation of the feed screw.

I have overcome the above-mentioned difficulties in part by placing arib lll in the retort as shown in Figs. 2-5, which rib as shown extendsdownwardly at any angle along one side of the throat I9 of the retortandapproximately along thejuncture of the throat wall and the wall ofthe retort bowl. This rib, as will .be understood in Figs. 4 and 5, isgradually curved on its forward and rear sides tomerge intothe retortwall il` and the'wall i9 of the throat,.respectively, asshown at 2U and2l in Fig.. 4. Asv seen in Fig. 5, the inner edge of the rib I8 extendsinwardly a substantial distance with relation to the circumferenceor'wall 23` of the.` coal tube, and the rib extends'from the bottom 24of the retort throat i9 tog-the upper side ofthe throat I9. A neckportion 22`of the retort is preferably'flared as shown at23ito form agraduallyenlarging entrance into the retort bowl from the coal'tube.

`Wth a feed screw as shown, rotating in a clockwise direction asviewed'in Fig. 5, the front end of the screw acts'to push the coalforwardly intov` the retort but also in a predominantly upward?direction on the left hand side only of the axis of the. screw. Byplacing rib I8 adjacent the juncture of the neck with the retort, themovement of; coal from thescrew is diverted in such a way thatsubstantially equal amounts move towards both sides of the retort andthe coal is liftedl by the action of the screw conveyor and rib intothe-narrow angular channel which forms the retort throat'. In thiswaythe coalis not only evenly distributed in the retort, but also entersthe retort with'a minimum of segregation. The neck and throat beingyflared as shown. in the drawings', this provides: room for the coal torise and be distributed as referred to above, instead of `packingtightly. The. rib` holds back the coal so thatit may riseon the screw tothe top of the screw and then be ejected' upwardly; The coal. is thuslifte'dup into the throat rather than pushed directly from the coal tubeto rise too fast up the back side of the retort. This action of the coalin the throat continues until the coal is about levelr with the throatand then part of the coal lifts up through the throat and part is pushedover the heel 24 of the retort so that the coal rises uniformly inparallel strata to evenly distribute the coal in the retort and to riseto the top thereof' with a crownedsurface. This equalizes thedistribution ofy the coal' and prevents segregation of the largerparticles from the smaller particles which remain thoroughly mixed.

Formed centrally of the upper side of the coal tube 3 and spacedlongitudinally within the casing 1 are two hollow members 25 and 26, theadjacent top side of the coal tube having a pair of slots 21 and 28leading from the hollow interior of these members to the interior of thecoal tube. Member 25 is formed in each of its lateral sides withopenings 29 and 30 whereby air under pressure may be forced from theinterior of the hollow casing 1 through slot 21 to the interior ofk thecoal tube to create a pressure of air in the coal tube toward theretort. This tends to drive any smoke or gases of combustion coming fromthe retort in the opposite direction, that is, away from the hopper andback toward the retort, due to thefact that coal entering the coal tubefrom: the hopper isk tightly packed at the spike trap. Screwed into thetop of member 26 is a pipe 3| leadingto theinterior of the hollow member26' and communicating with the slot 28, the other end of the pipegenerally communicating with the interior of the furnace or connected inany manner with the flue so as to take advantage of its suction, throughpipe 3l, which will in turn create a focal discharge point at slot 28for smoke or gases of combustion from the interior of the coal tube andlead the same into the furnace or flue to eventually pass out throughthe flue. The sides of the member 26 will preferably be closed by plugs32 to prevent entry of air from the interior of the casing 1 to theinterior of the pipe 3| so that the only passage into pipe 3l will bethroughslot 28 and through the hollow interior of member 26. Thisconstruction forms an efficient` means for preventing the passage ofsmoke-or gases of combustion backwardly from the retort to the hopper.

Il claim:

1. A stoker comprising a hopper, a fuel tube, a screw conveyer in thetube, a retort having a heel wall, an outwardly flaring neck having athroat betweenvthe tube and the retort, and a rib positioned on the wallof the retort adjacent the throat and near the upwardly movable side ofthe screw, and extending upwardly along one side of the neck, said ribbeing formed with a gradual curve onits'twosides mergingv into therespective walls of: the neck and the retort and at its ends merginginto the throat and heel walls respectively, and having. its edgeextending inwardly and gradually increasingv from` bottom to top andextending inwardly a substantial distance at the top,.the screw whentheneck is full of fuel lifting up part of the fuel into the throat atthe rib side and pushing part of it along the bottom of the retort sothatthe fuel rises to the top of the retort with a crowned. surface inuniform upward distribution.

2. Astoker comprising a tube adapted to have fuel such as crushed coalforced therethrough, a rotatable screw for forcing said fuel through thetube, a retort at the outlet. end of the tube having a bowl and having aneck increasing in size from the diameter of, the tube to the lowerinterior of the bowl to form a throat at the junc-v ture ofthe neckv andbowl, and. means in the retort adjacent the throat thereof forobstructing free passage of the fuel into the retort bowl comprising arib in the-retort beginning at the upper side of the throat andextending downwardly at an angle and approximately along one side of thethroat at the juncture of the neck and the wall of the retort bowl, saidrib being gradually curved on its forward and rear sides to merge intothe wall of the retort.. bowl and the wall of theV neck respectively,and having its edgev extendingy inwardly and gradually increasing frombottom to top and extendinginwardly a substantial distance at the topand" stretching from the bottom of the retort bowl to the upper side ofthe throat.

3. A stoker comprising a tube adapted to have fuel such as crushed coalforced therethrough, a rotatable screw for forcing said fuel through thetube, a retort at the outlet end of the tube having a bowl and having aneck increasing in size from the diameter of the tube to the lowerinterior of the bowl to form a throat at the juncture of the neck andbowl, and means in the' retort adjacent the throat thereof forobstructing free passage of the fuel into the retort bowl comprising arib extending from a point near the bottom of the throat upwardly alongthe side along which the screw surface rises and merging into the wallof the throat above the top of the screw,

said rib being gradually curved on its forward l and rear sides to mergeinto the retort wall and the wall of the throat respectively, and havingits edge extending inwardly and gradually increasing from bottom to topand extending inwardly a substantial distance at the top.

4. A stoker comprising a fuel tube, a rotatable screw in the tube forforcing fuel such as crushed coal therethrough, a retort at the outletend of the tube and having a bowl, a neck gradually enlarging in sizefrom the inside diameter of the tube to the lower interior of the bowlto form a throat at the juncture of the neck and bowl, and means in theretort adjacent said throat for equalizing the distribution of fuelupwardly in the retort comprising a rib extending from the bottom of thethroat diagonally upwardly and rearwardly of the throat to a pointhigher than and to one side of the screw, said rib having itslongitudinal free-edge concave, said free-edge extending inwardly andgradually increasing from bottom to top and extending inwardly asubstantial distance at the top and being gradually curved on itsforward and rear sides to merge into the wall of the retort bowl and thewall of the neck respectively.

CORNELIUS QUIST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,787,671 Daniels Jan. 6, 19311,830,798 Leach Nov. 10, 1931 1,856,557 Hoke et al. May 3, 19322,004,813 Jones June 11, 1935 2,028,274 Cross et al Jan. 21, 19362,039,389 Buskard May 5, 1936 2,051,282 Yerges Aug. 18, 1936 2,118,104Peck May 24, 1938 2,118,625 Scholl May 24, 1938 2,124,317 SchweickartJuly 19, 1938 2,272,438 Sourber Feb. 10, 1942

